Shortspike Canarygrass (Phalaris brachystachys) is a monocot weed in the Poaceae family. In Italy this weed first evolved resistance to Group A/1 herbicides in 2001 and infests Durum wheat, and Sugar beets. Group A/1 herbicides are known as ACCase inhibitors (Inhibition of acetyl CoA carboxylase (ACCase)). Research has shown that these particular biotypes are resistant to clodinafop-propargyl, diclofop-methyl, pinoxaden, and sethoxydim and they may be cross-resistant to other Group A/1 herbicides.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

The population collected in sugarbeet is cross-resistant to clodinafop, pinoxaden and sethoxydim while the ones collected in durum wheat are cross-resistant to tralkoxydim and diclofop. All population are controlled by ALS inhibitors.

Field, and Greenhouse trials comparing a known susceptible Shortspike Canarygrass biotype with this Shortspike Canarygrass biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

Genetic studies on Group A/1 resistant Shortspike Canarygrass have not been reported to the site. There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group A/1 resistant Shortspike Canarygrass from Italy please update the database.

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Italy have been instrumental in providing you this information. Particular thanks is given to Alberto Collavo for providing detailed information.

In Greece, diclofop-methyl was heavily used for grass weed control whereas chlorsulfuron was used for many years to control broad-leaf weeds in winter cereals. Recently, failures in control of several populations of major weeds were reported in Greece. The objectives of this research were to investigate the possibility of resistance evolution in various populations of Lolium rigidum, Phalaris brachistachys and Avena sterilis to grass herbicides and Papaver rhoeas to chlorsulfuron, and to elucidate the mechanisms of resistance. Plant response to these herbicides was evaluated in pot experiments and laboratory studies. We found that L. rigidum is multiple-resistant to ACCase inhibitors due to an altered target site, and to chlorsulfuron due to enhanced detoxification. Eight biotypes of P. brachystachys, were examined for resistance to ACCase inhibitors and seven of them indicated resistance to fenoxaprop-ethyl. In contrast all eight biotypes were susceptible to tralkoxydim and clodinafop-propargyl. Continuous use of isoproturon resulted in heavy infestation with A. sterilis that tolerates high rates of isoproturon while being susceptible to ACCase inhibitors used. A population of P. rhoeas was found to be resistant to chlosulfuron (altered target site), whereas all P. rhoeas populations were susceptible to imazamox and tolerant to imazapic but resistant plants were cross-resistant to imazethapyr..

Phalaris brachystachys and Phalaris minor are common and troublesome weeds in winter cereals in Mediterranean countries. Different distribution and soil preferences have been found for each species in Andalusia (southern Spain). In irrigated fields P. minor is more frequent while P. brachystachys has extended its range to semiarid provinces with low rainfall. This different adaptation to irrigation conditions is difficult to explain considering aspects of their biology, herbicide tolerance, or cultivation practices. The objective of this study was to assess the influence of different soil water availabilities over growth and reproductive aspects to explain the differences found in ecology and distribution of P. brachystachys and P. minor. The experiment was conducted under greenhouse controlled conditions using five levels of water availability: field capacity, light drought, moderate drought, severe drought and extreme drought. Differences between species and among treatments were found in plant height, biomass, tiller number, and reproductive traits. Field capacity and light drought treatments favoured biomass, tiller number, and panicle number in P. minor. In contrast, P. brachystachys had a positive response only in moderate drought and increased the percentage of mature panicle with increasing drought levels. These results could explain the wider distribution of P. brachystachys in fields without supplemental irrigation in semiarid areas, due to its adaptation to moderate drought conditions. It may also clarify the greater frequency of P. minor in irrigated fields and in areas with higher rainfall..

This study was carried out between 2008-2009 to determine the resistance of an important weed species. Phalaris brachystachys Link, in wheat fields in Cukurova Region, against some herbicides used in wheat. Resistance population was collected from Oksuzlu Village of Kadirli Town of Çukurova and susceptible population was collected from places such as road side and bare areas where no herbicide has been applied. In study three ACCase inhibitor herbicides (clodinafop-propargyl, pinoxaden ve tralkoxydim) and two ALS inhibitor herbicides (mesosulfuron-methyl+iodosulfuron-methyl-sodium, pyroxsulam+cloquintocet-sodium) were used. Each herbicide was applied at six different doses. Resistance index of resistant population was determined as 11.56 and 10.89 for clodinafo-propargyl at first and second year respectively, and as 8.51 and 2.13 for pyroxsulam+cloquintocet-sodium. Although no resistance have been proved for pinoxaden, tralkoxydim and mesosulfuron-methyl+iodosulfuron-metyl-sodium. These results suggested that particular attention should be given for the use of these three herbicides and treatments should be done at right time and consciously..